TPH-distorted peaks

[pueblito]

Dear Chromatographers.

We have some problems with an Agilent 6890N ( FID, software version B.04.02 SP1 (212)), that we use for TPH analysis.
The run starts at 40°C, but from time to time the sample is injected many degrees before (around 75°C) the initial temperature.

Any Idea about what is happening?

Thank you.

[Don_Hilton]

Sonunds like you have an autosampler that is not waiting for the system ready siganl. What kind of autosampler do you have?

[pueblito]

Dear Don.

These are:

7683 ( G2614A) autosampler.
7683B (G2913A) autoinjector.

[Don_Hilton]

I assume that is is an injection that is to be made when the GC reaches the ready status? And you are using ChemStation or MassHunter?

Don

[pueblito]

That is right, the injection starts when the GC reaches the ready status, and it is a GC-ChemStation software.

[Peter Apps]

Isn't there a setting somewhere that tells the automation whether to wait for the GC to be ready ? If there is you probably have it set wrong.

Peter

[Steve Reimer]

If it is intermittent, then check the cable connections. Somewhere you are getting a start or ready signal before the GC is ready.

[pueblito]

Thank you all for your help.

Best regards.